That led to a lot of questions about what deer-antler spray is and why athletes use it.

Here is an explainer.

What is deer-antler spray?

Deer-antler spray is a substance made of antler extract that you spray under your tongue.

Why do athletes use it?

Athletes take it for the same reasons they take HGH — it builds muscle and makes you bigger, stronger, and faster, according to the companies that make it. It contains IGF-1, which is a natural growth factor that's really similar to HGH.

Won't they test positive?

It's almost impossible to detect in drug tests, so the risk of getting caught is not that high.

Does it work?

Scientists are skeptical. People with certain medical conditions take IGF-1 shots, but doctors question whether or not it works in any other form. Dr. Roberto Salvatori told the Baltimore Sun that you can't even deliver IGF-1 orally, saying, “If there were [a spray that worked], a lot of people would be happy that they don’t need to get shots anymore. It’s just simply not possible for it to come from a spray.”

So it's a scam?

Well, not exactly a scam. But it falls into the gray area of "all natural" sports medicine with things like negatively charged water, wrist magnets, and special underwear that has been exposed to radio waves. S.W.A.T.S. — the company that allegedly gave Lewis the spray — sells a lot of things like that.

And they're just allowed to sell a banned substance like that?

"Banned" is different from "illegal." The companies that sell it get it approved by the FDA as a food, not a medicine. They can sell it anyone, but athletes are barred by their respective leagues from taking it.

How does one make deer-antler spray?

They clip off the deer antlers and either grind them, freeze them, or cook them to get out the nutrients, according to the Baltimore Sun. Deer velvet was a common ingredient in old Eastern medicine.